The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Besides the conventional cast material, alternative plastic-based dressing materials have been used for a long time. They are more advantageous than plaster casts because they have improved mechanical properties and are water-resistant, consequently washable, and owing to their rapid adjustability and hardening and low weight also ensure increased wearing comfort and improved mobility. Moreover, unlike plaster cast materials, they are X-ray permeable and thus allow X-ray examinations without having to remove the dressing. In this connection, conventional plaster cast materials as well as plastic-based dressing materials are essentially composed of an organic or inorganic textile carrier material and a plaster and/or plastic material applied thereon, whereas the plastic materials have to be differentiated between irreversibly hardening and reversibly deformable materials.
Water hardening polyurethane systems are primarily known as irreversibly hardening plastic materials, in which case the dressing materials harden within some time after being immersed in water, which allows the dressing material to be professionally applied and adapted to the person's or animal's body. As long as the plastic has not hardened, the individual layers of the dressing material may be bonded together, ultimately obtaining a dressing that consists of several layers.
With thermoplastic, reversibly deformable dressing materials like those to be used in the present disclosure, the self-adhesive properties are achieved by heating the thermoplastic plastic to or above the respective softening temperature. The material again hardens on cooling, in which case it may still be molded at temperatures below the melting point for some time. After the thermoplastic resin hardens, a dressing system with multiple layers bonded to one another is obtained.
In this case, the irreversibly hardenable polyurethane-based materials have certain disadvantages when compared to the thermoplastic materials because due to the water hardening properties, moisture-free production and complex product packaging, which make the package impervious to water and air, are required. Moreover, the corresponding resin formulations are relatively expensive and, if maximum possible moisture-free conditions are complied with, the storage stability is comparatively low. Polyurethane resins may further irritate the skin and cause noxious effects because of their isocyanate content.
An equivalent orthopedic splint as well as cast material is, for example, known from WO 02/054983. The cast material used in that case is a water hardening system, which mostly contains reactive polyurethane pre-polymers as hardenable plastic components, which irreversibly harden on contact with water. In contrast, DE 199 07 043 B4 protects a thermoplastic dressing material, which consists of a textile substrate coated with thermoplastic material, and ready-made as rolls. It may be supplied in a so called dispenser or dispensing container and be removed as quasi endless tape in the form of a flat material web.